Because reporting an assault is an undeniable act of agency, the default response is to undermine that act of empowerment and to doubt and discredit the individual. This is why we insist survivors "must have done something to provoke that assault" - that either she wasn't really assaulted at all, that it wasn't coercive - or that it was coercive but who cares because she's a slut and was behaving inappropriately in the first place.